Long Term Evolution (LTE) is a standard for wireless communication in which the communication is based on orthogonal frequency division multiplex (OFDM). OFDM provides an efficient use of the available communication resources in that communication resources are shared between all users. The communication resources can be in time-domain, in frequency-domain or in spatial-domain. A scheduler is used for allocating the different types of communication resources in view of various aspects, such as fairness among users, avoiding congestion in the communication system and limiting interference.
A scheduling decision is made every transmission time interval (TTI) for each transmission and a weight is used to prioritize user equipment (UE) in time domain. The UE having the highest weight is the UE that will get the communication resources during that TTI. The weight may be calculated in accordance with a scheduling strategy implemented in the scheduler, and examples of such scheduling strategies comprise Round Robin (RR) and Proportional Fair (PF). Different scheduling strategies use different inputs in the weight calculation. A scheduler implementing PF considers the user bit rate and channel quality when calculating the weight, while a scheduler implementing RR depends on elapsed time since last scheduled time for a particular UE thus achieving a pure fairness. The weight is calculated every TTI, helping make the scheduling decision for each transmission.
Using the RR and PF algorithms, the weight of a UE typically decreases once the UE gets scheduled and it is therefore unlikely that it will get the highest weight in the next TTI. In most scenarios the UE will be scheduled and then after a while it gets scheduled again, and so on until its buffer is empty, as illustrated in FIG. 1. For example, a first UE is scheduled at odd-numbered TTIs as illustrated by the upper line of arrows, and a second UE is scheduled at even-numbered TTIs as illustrated by the lower line of arrows. The first and second UEs are thus scheduled alternately. Although the known scheduling strategies provide a rather high fairness of use of the communication resources, they also entail a number of drawbacks.
For example, for a UE that needs many transmissions in total it might take hundreds of TTIs between the first and last transmissions and the total time for downloading or uploading may thus become long. During that time the UE has to listen to the potential scheduling, which results in high battery use.